The US government has criticised Lebanon's handling of a complaint filed against the Lebanese ambassador to Washington, Nada Moawad.
The case stems from a contact the envoy made with Israel's ambassador to Washington, Yechiel Leiter, to inquire about his son who was critically injured in a car-ramming attack at a checkpoint in the occupied West Bank.
A representative said the US State Department was aware of the complaint lodged by Hassan Adel Bazzi, whom Washington described as a "pro-Hezbollah lawyer".
The State Department said it was "embarrassing" that Lebanon's military court was handling the case.
Lebanon’s public prosecutor referred the complaint to the government commissioner to the military court, a procedural step that does not itself constitute a prosecution or referral for investigation, according to Lebanese media.
The two ambassadors have been at the forefront of direct negotiations between Israel and Lebanon, which have technically been in a state of war since 1948.
The talks were supposed to pave the way for Israel's withdrawal from south Lebanon and the disarmament of Hezbollah, two goals that have been almost entirely unsuccessful.
Some in Lebanon, including Hezbollah and its supporters, have been deeply critical of the government for engaging in negotiations with Israel.
"The Lebanese military judiciary should use its limited resources to prosecute Hezbollah operatives plotting against the Lebanese government and people instead of those working on their behalf," the State Department said.
"Laws and practices that enable this kind of politicised targeting of civilians and diplomats, while systematically shielding Hezbollah operatives, must be repealed. We have no patience for obstruction."
Lebanon's military court has in the past been accused of being influenced by Hezbollah.
The court is investigating two men whose vehicle was stopped last week with half a tonne of explosives bound for Beirut's southern suburbs, where Hezbollah holds sway.